Engines, including diesel engines, gasoline engines, natural gas engines, and other engines known in the art, may exhaust a complex mixture of air pollutants. The air pollutants may be composed of gaseous compounds, which may include nitrogen oxides, and solid particulate matter, which may include unburned hydrocarbon particulates called soot.
Due to increased attention on the environment, exhaust emission standards have become more stringent. The amount of air pollutants emitted from an engine may be regulated depending on the type of engine, size of engine, and/or class of engine. One method that has been implemented by engine manufacturers to comply with the regulation of particulate matter exhausted to the environment has been to develop new engines, which enhance swirl and air/fuel mixing while allowing for late fuel injections near top-dead-center (TDC).
One method of enhancing swirl is described in U.S. Pat. No. 6,152,101 (the '101 patent), issued to Parsi et al. on Nov. 28, 2000. The '101 patent describes a piston for an internal combustion engine, which has the capability of producing high gas velocities within a combustion chamber over a critical period of engine cycle near TDC. Specifically, the piston of the '101 patent has a combustion bowl with a first volume in communication with a second volume. The smallest diameter of a throat portion connecting the first and second volumes is smaller than the greatest diameter of the first volume and is smaller than the greatest diameter of the second volume. The greatest diameter of the first volume is greater than the diameter of a mouth of the combustion bowl. A wall means defining the first volume with respect to a piston crown face is less than 90 degrees.
Although the piston of the '101 patent may produce high gas velocities near TDC, it does not fully utilize a space above a face of the piston crown for swirling or mixing. In particular, because both the mouth and throat portion of the '101 patent have diameters less than diameters of the first and second volumes and because the wall means forms an angle that is less than 90 degrees with respect to the piston crown face, nearly all of the fuel injected into either of the first and second volumes is redirected radially inward toward a central portion of the piston rather than into the space above the face of the piston crown. Further, because the internal geometries of the first and second volumes have nearly identical contours, the direction of swirl within the piston cylinder caused by the first and second volumes may be limited. In addition, the piston of the '101 patent does not provide for a way to cool the piston.
The disclosed piston is directed to overcoming one or more of the problems set forth above.